Currently, to increase a capacity of a wireless communications market, the industry usually uses cell cluster deployment to enhance frequency reuse. A cell cluster is a service area in which multiple cells are deployed intensively. Deployment of the cell cluster may cause frequent cell handovers to a mobile device. Each cell periodically sends a system message, and the system message includes a basic access parameter of the cell. Each time when handed over to a cell, the mobile device needs to obtain system information of the cell, and access a network according to the system information of the cell. However, it is found in practice that when moving in the cell cluster, the mobile device usually needs to constantly read entire system information that is periodically broadcast by cells along the way. This not only brings high power consumption to the mobile device, but also reduces system information obtaining efficiency.